From the Guidelines
No, the Valsalva maneuver typically increases the intensity of hypertrophic obstructive cardiomyopathy (HOCM) murmurs rather than keeping them the same. During the strain phase of Valsalva, venous return to the heart decreases, reducing left ventricular volume. This exacerbates the dynamic left ventricular outflow tract obstruction characteristic of HOCM, causing the murmur to become louder, as noted in the guidelines by the American College of Cardiology/American Heart Association task force 1. This occurs because the smaller ventricular cavity brings the hypertrophied septum closer to the anterior mitral valve leaflet, worsening the obstruction.
The key points to consider are:
- The Valsalva maneuver decreases venous return, which reduces left ventricular volume and exacerbates the dynamic left ventricular outflow tract obstruction in HOCM.
- This response differs from other murmurs like aortic stenosis, which typically decrease in intensity with Valsalva, as outlined in the guidelines 1.
- Clinicians use this distinctive response to Valsalva as a diagnostic tool to differentiate HOCM from other cardiac conditions.
- Other maneuvers that reduce preload or afterload, such as standing from a squatting position, can produce similar intensification of HOCM murmurs through the same mechanism, as discussed in the guidelines 1.
From the Research
Valsalva Maneuver and HOCM Murmur Intensity
- The Valsalva maneuver is used to provoke left ventricular outflow tract obstruction in hypertrophic cardiomyopathy (HCM) and can affect the intensity of the HOCM murmur 2, 3.
- A study found that a standardized, goal-directed Valsalva maneuver (GDV) can provoke left ventricular outflow tract obstruction and increase the peak left ventricular outflow tract gradient (pLVOTG) in patients with HCM 3.
- The GDV was shown to be more effective than the self-directed Valsalva maneuver (SDV) in provoking obstruction and reclassifying disease severity 3.
- The Valsalva maneuver can also be used to evaluate heart murmurs and left ventricular function, and its response can provide insight into underlying hemodynamics 4.
- The technique of the Valsalva maneuver can influence the pattern of cardiovascular response, and variations in technique can affect the intensity of the murmur 5.
Mechanism of Valsalva Maneuver on HOCM Murmur
- The Valsalva maneuver increases intraoral and intrathoracic pressure, which can provoke left ventricular outflow tract obstruction and increase the intensity of the HOCM murmur 6.
- The maneuver can also cause complex cardiovascular and physiologic changes, including changes in heart rate and blood pressure 6, 5.
- The magnitude of the cardiovascular response to the Valsalva maneuver correlates with the strain duration and pressure, and depends on the baseline level of cardiovascular parameters and their variations 5.